BS 5116-1974 Method of test for determination of breaking tenacity of flat bundles of cotton fibres《棉花平列纤维束断裂强度的测定试验方法》.pdf

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1、BRITISH STANDARD BS 5116:1974 Method of test for Determination of breaking tenacity of flat bundles of cotton fibres UDC 677.017.424.7:677.21486.4BS5116:1974 This British Standard, having been approved by the Textile Divisional Council, was publishedunder the authorityofthe ExecutiveBoardon 19July19

2、74 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference T/16 Draft for comment73/70333 ISBN 0 580 08496 5 Co-operating organizations The Textile Divisional Council, under whose supervision this British Standard was prepared, consists of representatives fr

3、om the following Government department and scientific and industrial organizations: British Railways Board Consumers Association Consumer Standards Advisory Committee of BSI Cotton Industry Standards Committee Jute Industry Standards Committee Linen Industry Standards Committee London Transport Exec

4、utive Man-made Fibres Industry Standards Committee Ministry of Defence* Ropes and Cordage Industry Standards Committee Silk Industry Standards Committee Society of Dyers and Colourists* Textile Institute* Textile Machinery Industry Standards Committee Trades Union Congress Wool Industry Standards Co

5、mmittee The Government department and the organizations marked with an asterisk in the above list are represented on the Standing Joint Committee for Textile Test Methods, the members of which were appointed by the Textile Institute and the Textile Divisional Council, and which was entrusted with su

6、pervising the preparation of this British Standard. They were drawn from: Cotton Silk and Man-made Fibres Research Association Manchester Chamber of Commerce Testing House University of Leeds Wira Individual companies Amendments issued since publication Amd. No. Date of issue CommentsBS5116:1974 BSI

7、 09-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Apparatus 1 4 Atmosphere for conditioning and testing 2 5 Sampling and conditioning 2 6 Test specimens 2 7 Use of standard calibration cotton samples 2 8 Procedure 2 9 Calculation and expre

8、ssion of results 3 10 Test report 4 Appendix A Description and operation of the Pressley fibre strength tester 5 Appendix B Description and operation of the Stelometer 5 Publications referred to Inside back coverBS5116:1974 ii BSI 09-1999 Foreword This British Standard implements International Stand

9、ard ISO3060, “Cotton fibres: Determination of breaking tenacity of flat bundles” of the International Organization for Standardization (ISO). It is difficult and time consuming to estimate the average breaking tenacity of samples of cotton from tests on individual fibres. For both commercial and tec

10、hnical purposes, quicker estimates may be obtained from determinations made on flat bundles of parallel fibres. In this procedure, short fibres are combed out and the measured fibre strength corresponds with the breaking strength of the longer fibres in the sample. The bundles of fibres may be secur

11、ed by clamps which are either in close contact (zero gauge length) or separated to give a specified nominal gauge length. Fibre strength testing at zero gauge length is current commercial practice, although some investigations suggest that tests at a gauge length of3.2mm are more closely related to

12、the tenacity of many classes of cotton yarn. International Calibration Cotton Standards for zero gauge and national Calibration Cotton Standards for3.2mm gauge have been established to enable different operators to adjust their personal levels of testing to an agreed common level. These standards ma

13、y also be used by operators to adjust the level of test results obtained from measurements made on instruments with different rates of loading to the agreed level for this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards

14、are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard h

15、as been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS5116:1974 BSI 09-1999 1 1 Scope This British Standard specifies a method of test for the determination of the breaking tenacity of cotton fibres ar

16、ranged in a parallel manner in a flat bundle. The method applies either to fibres from raw cotton, or to fibres from various stages in the manufacturing process, or to fibres separated or extracted from manufactured cotton products. The method is applicable to fibres being tested either at a nominal

17、 gauge length of zero or at a finite gauge length. The method is especially intended to be used with tensile strength test instruments which have been designed for specific use on flat bundles of cotton fibres (seeAppendix A and Appendix B). It may be used with other tensile strength test instrument

18、s if they are equipped with adaptors to accommodate the fibre clamps. NOTEThe titles of the British Standards referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard the following definitions apply: gauge length the length of a specim

19、en under specified pre-tension measured from nip-to-nip of the jaws of holding clamps in their starting position at the beginning of the test breaking load the maximum load (force) applied to a specimen in a tensile test carried to rupture tensile strength the strength shown by a specimen subjected

20、to tension (as distinct from torsion, compression or shear), and expressed as force per unit cross-sectional area of the unstrained specimen tenacity the tensile force per unit of linear density of the unstrained specimen, expressed in centinewtons per tex breaking tenacity the tenacity correspondin

21、g to the breaking load 3 Apparatus The following are required: a) Tensile testing instrument suitable for determining the breaking load of a flat bundle of fibres to an accuracy of0.5%. NOTETwo commercially available fibre bundle strength test instruments are described in Appendix A and Appendix B.

22、Other tensile testing instruments may be used if equipped with adapters to accommodate the fibre clamps. b) Specimen clamps, which can be removed from the test instrument. A total clamp thickness of11.8mm and a spacer with a thickness of3.2mm are recommended because the precision data (see9.2) are b

23、ased on clamps of these dimensions. The clamps should be faced with leather or other suitable material. c) Clamp vice, consisting of a jig equipped with a locking screw or cam for holding the clamps while they are being loaded and unloaded. A vice having a device to indicate approximately9daN cm tor

24、que is recommended. d) Balance, sensitive to 0.01mg. A capacity of3mg to5mg is sufficient for most fibre bundle strength tests, but balances having a larger capacity may be used if they have the required sensitivity. e) Coarse comb, approximately3teeth per centimetre, or comb used with length testin

25、g instruments. f) Fine comb, approximately20teeth per centimetre. g) Wrench for tightening the clamps. A torque wrench is needed if the clamp vice is not equipped with a torque device seec). h) Shearing knife. j) Tweezers.BS5116:1974 2 BSI 09-1999 k) Standard calibration samples, having specified or

26、 agreed strength values 1) . 4 Atmosphere for conditioning and testing The atmosphere for conditioning and testing shall be the standard atmosphere for conditioning and testing textiles as defined in BS1051. This atmosphere has a relative humidity of65 2% and a temperature of20 2 C. 5 Sampling and c

27、onditioning 5.1 Select the sample of cotton for testing in accordance with the method prescribed in BS2545, or in other ways as agreed by the interested parties. 5.2 Bring the laboratory sample into equilibrium with the standard atmosphere for conditioning and testing textiles as defined in Clause4,

28、 starting from a dry state. A minimum of4h conditioning time is normally required. NOTECotton is normally received at the laboratory in a relatively dry condition; for this reason, special preconditioning is not specified. Samples which obviously have more moisture should be subjected to preconditio

29、ning before conditioning in the laboratory. The preconditioning atmosphere should have a relative humidity between10% and25% at a temperature not higher than50 C. An atmosphere with a relative humidity of65% at20 C will give this preconditioning atmosphere when heated to47 3 C. 6 Test specimens Take

30、 the test specimens (flat bundles) from small sub-samples (tufts or beards prepared for use in length testing) which have been prepared from the laboratory sample as directed below. Prepare a tuft by taking, for example,16 small pinches at random from the laboratory sample and blending them by succe

31、ssive doubling and dividing. When one end of the tuft has been combed, reverse the tuft and comb the other end, making sure that the middle portion of the tuft is well combed. Approximately ten strokes are necessary for combing each end of the tuft. Prepare at least six specimens. NOTEPreferably car

32、ry out the test with the participation of two operatives, each testing three tufts; with three operatives each carrying out one test on two tufts, greater reliability is achieved. 7 Use of standard calibration cotton samples Each day, before carrying out other tests, make a check test of at least th

33、ree specimens per technician on one or more standard calibration samples to check the reproducibility and uniformity of results. If available, use standard calibration samples with test values within the range of the unknown samples being tested. Make additional check tests in a similar manner at le

34、ast three more times during a working day to obtain results for the calculation of correction factors. The calculated breaking tenacity values of the samples tested during the same period can be adjusted to the standard level by applying the correction factor (see9.1.3) calculated from the check tes

35、t. This factor is used to adjust the level of observed results for operator, instrument and other uncontrolled sources of difference in testing. 8 Procedure 8.1 Check the test instrument and clamp vice for mechanical adjustment in accordance with the manufacturers instructions, or as directed for sp

36、ecific instruments described in Appendix A and Appendix B. 8.2 Inspect the clamp leathers to ensure that they are in good condition. Replace the leathers if grooves are evident. Keep the leathers trimmed flush with the metal surfaces of the clamps. 1) International Calibration Cotton Standards for z

37、ero gauge tests and United States Calibration Cotton Standards for3.2mm gauge tests are available from the US Dept of Agriculture, Agricultural Marketing Service, Cotton Division, Box17723, Memphis, Tennessee38117, USA.BS5116:1974 BSI 09-1999 3 8.3 Prepare the test specimen as follows. Grasp the pre

38、pared tuft about one-fourth the distance from the end of the tuft and pull out a portion of the fibres. Hold these extracted fibres firmly by one end and pull them through the fine comb two or three times to remove loose fibres, neps, and trash. The depth of penetration of the comb teeth into the tu

39、ft should be regulated to ensure minimum fibre breakage. Comb the other end of the specimen in the same manner, keeping the fibre ends aligned while the middle portion is combed. Maintain the width of the specimen at approximately6mm. If the specimen is too heavy, remove fibres from either side to o

40、btain the correct mass. The specimen is now ready to be placed in the clamps. NOTEThe preparation of the tuft for3.2mm length of test poses problems in the case of fibres of short length. Except in the case where precautions are taken to include only long fibres, certain fibres in the tuft cannot be

41、 held in the jaws with their ends protruding on the other side. 8.4 Place the test specimen in the fibre clamps as directed in either7.4.1 or7.4.2. 8.4.1 Using a vice without a pre-tensioning device, lock the clamps in the vice and open the clamps. Hold both ends of the specimen, keeping it approxim

42、ately6mm wide, and place it in the centre of the open clamps. Apply sufficient tension to hold the fibres straight while the jaws of the clamps are lowered and tightened in place by applying a9daN cm torque. The torque may be controlled either by a vice-mounted torque-indicating attachment, or by a

43、friction-disc wrench. Remove the clamps from the vice. Shear off the protruding ends of the specimen with the shearing knife, shearing downward and away from the leather face of the clamps. 8.4.2 Using a vice with a pre-tensioning device, lock the clamps in the vice and then open the clamps. Lift th

44、e fixed clamp on the vice and insert the loose ends of the flat bundle specimen held in the fibre clip. Draw the fibre clip forward until it falls into place over the back of the tension lever. Apply sufficient pressure on the fixed clamp to prevent fibre slippage and release the ring lever to apply

45、 tension on the specimen. Close and tighten the clamps, applying a torque of9daNcm. Tighten the clamp farthest from the clip first to ensure correct tension between the clamps. Remove the clamps from the vice and shear off the protruding fibres as described in8.4.1. 8.5 Insert the prepared clamps in

46、 the strength testing instrument and break the test specimen in accordance with the instructions furnished by the manufacturers of specific instruments (seeAppendix A and Appendix B). When the specimen has broken, record the breaking load. Remove the clamps from the instrument, check to seethat all

47、fibres are broken, and place the clamps in the vice. If all fibres are not broken, or are broken irregularly (i.e.an irregular cut forming an angle with the jaws of the clamp), or if the breaking load is less than the required minimum for the instrument used, discard the specimen and make a new test

48、. If the break is acceptable, open the clamps, collect the broken fibres with tweezers and determine their mass to the nearest0.01mg (seeNote). Collect all the fibres so that the correct mass may be obtained. To avoid a gain in mass from moisture pick-up, do not touch the fibres with the fingers whi

49、le collecting and determining the mass of the specimen. NOTEIf desired, the broken specimens may be placed temporarily in folded black papers, kept in the standard atmosphere for testing, and their mass determined. 9 Calculation and expression of results 9.1 Method of calculation 9.1.1 Unadjusted breaking tenacity. Calculate for each specimen the unadjusted breaking tenacity, in centinewtons per tex, by the following formulae: a) for zero gauge length tests, based on a bundle length of11.8mm, breaking tenacity= b) for3.2mm gauge length tests, based on a bundle length